Over time, integrated circuits are becoming smaller and have increased capabilities. The production of smaller integrated circuits requires the development of smaller electronic components, and closer spacing of those electronic components. In traditional integrated circuits, electrical contacts are formed through an insulating cover layer, often called an interlayer dielectric, to connect the electronic components in a desired manner. Some electronic components have multiple electrical contacts, such as a field effect transistor (FET) that may have contacts to its source, its drain, and its gate. The contacts must be spaced very close together to make the desired electrical connections.
Electrical contacts typically physically connect electrical devices on one layer of the integrated circuit to interconnect or metallization layers spaced from the devices by one or more of the interlayer dielectric layers. There may be several layers of interconnect lines separated by interlayer dielectrics, and there may be transistors, resistors, and other electronic components separated by various other layers of interlayer dielectric as well. The contacts are formed by etching a via or hole in the interlayer dielectric material, and then depositing conductive material in the via.
The vias are positioned by patterning a photoresist layer to expose desired areas of the interlayer dielectric, and using the patterned photoresist as a mask for the etching process. In a traditional process, the contacts are formed by depositing a layer of photoresist, exposing desired area of the photoresist to light to change the chemical nature of the photoresist, and then removing the photoresist from either the areas exposed to the light or the areas protected from the light. A mask is used to protect selected areas of the photoresist from light, and to allow light to pass through to other areas. When the mask is designed to transmit light through small areas that approach the wavelength of the light, the light refracts or bends when it passes through the mask and contacts photoresist that the mask is intended to shield. The result in a resolution limit at which the photoresist pattern cannot be scaled below. Shorter frequency light can be used to lower the resolution limit, but there is a higher cost for using shorter frequency light. Even with short frequency light, the spacing of the vias is limited by the resolution limit. This resolution limit, and the associated limit on how close electrical contacts can be placed, can prevent the production of integrated circuits with electronic components packed beyond a certain distance from each other.
Accordingly, it is desirable to develop methods and systems for manufacturing contacts close together. In addition, it is desirable to develop methods and systems for contacts spaced closer together than the resolution limit of the photoresist used. Furthermore, other desirable features and characteristics of the present embodiment will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.